Question 22

[eo5]

how do you know what the initial intnsity is?

[admin]

This is a test question.

If you already knew that Io, the threshold intensity, is defined as barely audible, 0 decibels (dB) and 10 exp-12 then you would know that there is only one possible answer (no calculation is required because the answer must be greater than 10 exp-12).

In fact, normally when the MCAT has the equation to calculate loudness, they give it to you (in other words, it's on the list of equations to understand but not necessarily to memorize). How do you understand it? You need to know what Io stands for and you need to be comfortable manipulating logarithms.

[admin]

Good pick up! It was not intentional and it has been updated.

[admin]

Just think of Io like any other constant (the speed of light c or the density of water or the gas contant R). Io, the threshold intensity, is defined as barely audible, 0 decibels (dB) and 10 exp-12 W/m2.